CN109725779B

CN109725779B - Touch detection device and method for detecting touch

Info

Publication number: CN109725779B
Application number: CN201811152963.8A
Authority: CN
Inventors: 南常必; 李炅勋; 崔炳
Original assignee: Samsung Electronics Co Ltd
Current assignee: Samsung Electronics Co Ltd
Priority date: 2017-09-29
Filing date: 2018-09-28
Publication date: 2023-12-12
Anticipated expiration: 2038-09-28
Also published as: US20190102034A1; CN109725779A; KR102452620B1; US10936118B2; KR20190038187A

Abstract

A touch detection apparatus and a method of detecting a touch employ: a current-to-voltage converter configured to convert a reception signal received from the touch panel into a sensing signal, and further configured to periodically reset for a first period of time in response to a reset signal; an analog-to-digital converter configured to convert an analog signal based on the sensing signal into a first digital output signal; and a controller configured to generate a second digital output signal based on the first digital output signal by performing data interpolation on a first portion of the first digital output signal corresponding to the first period of time.

Description

Touch detection device and method for detecting touch

Cross Reference to Related Applications

The present application claims priority from korean patent application No. 10-2017-0128305 filed in the korean intellectual property office on 29 th 2017, the disclosure of which is incorporated herein by reference in its entirety.

Technical Field

The inventive concept of the present disclosure relates to touch detection of a pointer, and more particularly, to a touch detection apparatus and a method of detecting a touch.

Background

Touch panels are mounted on various electronic devices. The touch panel may provide an area where a pointer external to the electronic device may touch, and may include a plurality of electrodes for detecting the pointer. Touch coordinates of a pointer touched on the touch panel may be identified by processing signals provided from at least one of a plurality of electrodes in the touch panel. Further, when the pointer touches on the touch panel, the electronic device may additionally provide various functions by recognizing the touch pressure caused by the pointer and the touch coordinates. The signal provided from the touch panel may include noise generated inside and/or outside the electronic device, and by removing the noise, the touch of the pointer may be more accurately detected.

Disclosure of Invention

According to one aspect of the inventive concept, there is provided an apparatus for more precisely detecting a touch of a pointer by reducing or removing display noise in a signal received from a touch panel.

According to another aspect of the inventive concept, there is provided a method of detecting a touch of a pointer more precisely by reducing or removing display noise in a signal received from a touch panel.

According to an aspect of the inventive concept, there is provided a touch detection apparatus including: a current-to-voltage converter configured to convert a reception signal received from the touch panel into a sensing signal and periodically reset for a first period of time in response to a reset signal; an analog-to-digital converter configured to convert an analog signal generated based on the sensing signal into a first digital output signal; and a controller configured to generate a second digital output signal based on the first digital output signal by performing data interpolation on a first portion of the first digital output signal, wherein the first portion of the first digital output signal corresponds to the first period of time.

According to another aspect of the inventive concept, there is provided a touch detection apparatus for processing a reception signal that varies with a touch of a pointer on a touch panel. The touch detection device includes: an analog front end configured to generate a first output signal by converting and amplifying a received signal, wherein the analog front end is periodically reset in response to a reset signal to generate the first output signal having a discontinuous data value; and a controller configured to generate a second output signal having a continuous data value by interpolating a discontinuous period of the first output signal having a discontinuous data value based on the data value of the continuous period, and further configured to detect a frequency of the second output signal.

According to another aspect of the inventive concept, there is provided a touch detection apparatus for processing a reception signal varying with a touch of a pointer on a touch panel, the touch detection apparatus including: an analog front end configured to generate a first output signal by converting and amplifying a received signal; and a controller configured to interpolate the second data value of the second period based on the first data value of the first period of the first output signal before the second period of the first output signal and the third data value of the third period of the first output signal after the second period.

According to another aspect of the inventive concept, there is provided a method of detecting a touch by processing a received signal that varies with a touch of a pointer on a touch panel. The method comprises the following steps: generating an output signal based on the received signal, wherein the output signal is a data value corresponding to a change in the received signal; generating a reconstructed output signal by interpolating at least one data value of a second period of the output signal between a first period of the output signal and a third period of the output signal based on the data value of the first period and the data value of the third period; and detecting the amplitude and frequency of the reconstructed output signal.

According to yet another aspect of the inventive concept, an apparatus comprises: an Analog Front End (AFE) configured to receive a received signal from the touch panel, wherein the received signal varies with a touch of the pointer on the touch panel, and in response thereto, output a first digital signal having a plurality of data values, wherein the plurality of data values varies with the touch of the pointer on the touch panel; and a controller configured to receive the first digital signal and output a second digital signal in response thereto, wherein the controller is configured to replace one or more of the data values of the first digital signal with interpolated data values to generate the second digital signal, wherein the one or more data values correspond to a first time period when a noise level in the received signal is greater than other time periods.

Drawings

Embodiments of the inventive concept will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings.

FIG. 1 is a block diagram of an example embodiment of a touch detection device.

Fig. 2 is a graph showing signal waveforms of the touch detection device of fig. 1 in a time domain.

Fig. 3A and 3B are diagrams illustrating an example embodiment of a data interpolation method.

Fig. 4 is a circuit diagram of an example embodiment of an Analog Front End (AFE).

Fig. 5 is a circuit diagram of another example embodiment of an AFE.

FIG. 6 is a block diagram of another example embodiment of a touch detection device.

Fig. 7 is a graph showing signal waveforms of the touch detection device of fig. 6 in a time domain.

Fig. 8 is a diagram for explaining display noise.

Fig. 9A, 9B, 9C, and 9D are graphs illustrating example embodiments of a timing signal and a reset signal.

FIG. 10 is a block diagram of an example embodiment of a touch detection circuit.

Fig. 11 is a graph showing a reset signal generation method of the signal generator in fig. 10.

FIG. 12 is a block diagram of another example embodiment of a touch detection circuit.

Fig. 13A, 13B and 13C are graphs showing internal signals of the AFE of fig. 12 in the frequency domain.

Fig. 14A and 14B are circuit diagrams of further example embodiments of AFE.

Fig. 15 is a flowchart of an example embodiment of a touch detection method.

FIG. 16 is a flowchart of another example embodiment of a touch detection method.

FIG. 17 is a block diagram of a system including an example embodiment of a touch detection device.

Fig. 18 is a block diagram of an example embodiment of a system.

Detailed Description

Embodiments of the present disclosure will be described below with reference to the accompanying drawings.

Fig. 1 is a block diagram of an example embodiment of a touch detection device 10, and fig. 2 is a graph showing signal waveforms of the touch detection device 10 of fig. 1 in the time domain.

The touch detection device 10 may be mounted on various electronic devices having a touch recognition function. For example, the touch detection device 10 may be installed on an electronic device such as a Personal Computer (PC), a web server, a tablet PC, an electronic reader, a Personal Digital Assistant (PDA), a Portable Multimedia Player (PMP), a mobile phone, an internet of things (IoT) device, a refrigerator, and a navigation device. Further, the touch detection device 10 may be mounted on an electronic device provided as part of a vehicle, furniture, manufacturing facility, door, and various measuring instruments.

Referring to fig. 1, the touch detection device 10 may include a touch panel 100, an Analog Front End (AFE) 210, and a controller 220. The AFE 210 and the controller 220 may constitute a touch detection circuit 200 that processes a reception signal RX (or an input signal) provided by the touch panel 100, thereby detecting a touch. The AFE 210 and the controller 220 may be integrated in one semiconductor chip or in different semiconductor chips. Although the touch detection device 10 of fig. 1 includes the touch panel 100, the touch detection circuit 200 including the AFE 210 and the controller 220 may be referred to as a touch detection device without the touch panel 100.

The touch panel 100 may include a plurality of electrodes 110. For example, the plurality of electrodes 110 may include a first electrode extending in a first direction and a second electrode extending in a second direction. The first electrode and the second electrode may each operate as a driving electrode for receiving a transmission signal from the outside and/or a sensing electrode for providing a reception signal to the outside of the touch panel 100.

Since the pointer or a signal supplied from the pointer changes capacitance, a sensing electrode disposed at a point of touching the pointer among the sensing electrodes may supply a reception signal different from other sensing electrodes. In other words, the reception signal RX may include a touch signal generated by the touch of the pointer. In this case, the touch of the pointer to the touch panel 100 may include not only a case where the pointer is in contact with the touch panel 100 but also a case where the pointer is close to the touch panel 100.

The pointer may refer to any object that may cause a received signal (e.g., a received signal RX) output by the touch panel 100 to change by touching or almost touching the touch panel 100. For example, the indicator may be a portion of a body part (e.g., a finger) of a user of the electronic device on which the touch detection device 10 is mounted, may be an item worn or used by the user (e.g., a glove, a stylus, or a stylus), or may be a portion of another system whose position varies with operation.

As described below, as the reception signal (e.g., reception signal RX) output by the touch panel 100 is processed, the touch pressure applied to the touch panel 100 by the pointer and the position of the pointer touched on the touch panel 100 (e.g., coordinates on the touch panel 100) may be recognized, and accordingly, the electronic device mounted with the touch detection device 10 may provide additional functions according to the pressure of the pointer.

The AFE 210 may receive a reception signal RX (or an input signal) from the touch panel 100 and may process the reception signal RX to generate an output signal DOUT corresponding to the reception signal RX. The reception signal RX received from the touch panel 100 may be an analog signal that varies in response to a touch of the pointer. For example, the reception signal RX may be an alternating current signal. The output signal DOUT may be a digital signal having a data value that varies with the variation of the received signal RX. The AFE 210 may convert the reception signal RX into the output signal DOUT including a digital value corresponding to the reception signal RX so that the controller 220 may easily detect the touch of the pointer. For example, AFE 210 may convert and/or amplify received signal RX and/or remove noise from received signal RX.

The AFE210 may include an input buffer 201, a filter 202, an amplifier 203, and an analog-to-digital converter 204 (hereinafter referred to as an ADC). The input buffer 201, the filter 202, the amplifier 203, and the ADC 204 may constitute one receiver for processing one reception signal RX provided from the touch panel 100. Although the AFE210 in fig. 1 includes one receiver for convenience of description, the AFE210 may receive a plurality of reception signals from the touch panel 100 and may include a plurality of receivers that process the plurality of reception signals at the same time. In an embodiment, the AFE210 may further include a transmitter providing a transmission signal to the electrode 110 of the touch panel 100.

The input buffer 201 may receive a touch signal by converting a reception signal RX supplied from the touch panel 100 into a sensing signal VS. In some embodiments, the receive signal RX may be a current signal and the sense signal VS may be a voltage signal. In that case, the input buffer 201 may be referred to as a current-voltage converter. The receive signal RX may be a varying alternating current. The input buffer 201 may function as a current amplifier or a current-to-voltage converter and generate a sense signal VS that varies according to or corresponding to the received signal RX.

Filter 202 may attenuate one or more of the bands of sense signal VS in order to reduce noise. The filter 202 may be a switched capacitor filter or a discrete time filter comprising a plurality of cell capacitors, and may be a continuous time filter comprising at least one active or passive element.

The filter 202 may have a set pass band and stop band, where the stop band has at least one cut-off frequency boundary. The reception signal RX may include a touch signal and noise according to or in response to a touch of the pointer, and the sensing signal VS generated by converting the reception signal RX may also include a touch signal and noise. The frequency band of the touch signal and the frequency band of the noise may be different from each other, and the set passband of the filter 202 may be set to include the frequency band due to the touch signal. Accordingly, the filter 202 may remove some or all of the frequency bands of the sensing signal VS due to noise, thereby generating a filter output signal FOUT including the touch signal and removing small noise or all of the noise.

The amplifier 203 may generate the analog output signal AOUT by amplifying the filter output signal FOUT with a set gain. The amplifier 203 may be implemented as a variable gain amplifier or a programmable gain amplifier. In an embodiment, the gain of the amplifier 203 may be set according to a control signal provided from the controller 220.

The ADC 204 may generate a digital output signal DOUT by digitally converting the analog output signal AOUT. The ADC 204 may sample the analog output signal AOUT based on the sampling frequency and convert the sampled value to a data value (or digital code). The sampling frequency may be set relatively higher than the frequency of the analog output signal AOUT so that the data values corresponding to the plurality of sampling values substantially reflect fluctuations of the analog output signal AOUT.

In an embodiment, AFE 210 may be reset (or held) for a predetermined period of time in response to a reset signal RST to avoid noise when processing a received signal RX, thereby generating a data signal DOUT.

Referring to fig. 2, the reception signal RX may include a touch signal, and noise may be in the reception signal RX. The reset signal RST may be set to have an active level, e.g., a high level, in a period (i.e., interval) in which noise is present in the reception signal RX. The period in which the reset signal RST has an active level, that is, the active period of the reset signal RST may be referred to as a reset period Trst. In an embodiment, noise may occur periodically in the received signal RX. Accordingly, the reset signal RST may be set to a periodic signal periodically having an active level.

In response to the reset signal RST, the AFE 210 may be reset in the reset period Trst. In the reset period Trst, the AFE 210 may not perform an operation of converting and amplifying the reception signal RX, thereby avoiding noise. Specifically, at least one of the input buffer 201, the filter 202, and the amplifier 203 provided in the AFE 210 may be reset in response to the reset signal RST. Accordingly, the data value (or data values) of the reset data period RP of the output signal DOUT corresponding to the reset period Trst of the reset signal RST may have a value independent of the reception signal RX. In an embodiment, the data value of the reset data period RP of the output signal DOUT may be constant.

Referring back to fig. 1, the controller 220 may control the AFE 210 and detect a touch of the pointer based on an output signal DOUT provided by the AFE 210 to generate a touch detection signal TDET. The controller 220 may be implemented with a digital signal processor, a microprocessor, a special purpose processor, or the like.

For example, the controller 220 may detect touch coordinates and touch pressure based on the amplitude and frequency of the output signal DOUT, and may generate a touch detection signal TDET including information about the touch coordinates and touch pressure. The controller 220 may control the reset of the AFE 210 by providing a reset signal RST to the AFE 210. The controller 220 may generate the reset signal RST based on a timing signal supplied from the outside, or may determine a period in which noise is present in the reception signal RX based on the output signal DOUT supplied from the AFE 210, and generate the reset signal RST based on a result of the determination. In addition, the controller 220 may set the gain of the amplifier 203.

As described above, when the AFE 210 is reset in response to the reset signal RST, since the data value (or data values) of the reset data period RP of the output signal DOUT is a value irrelevant to the reception signal RX, noise can be avoided, but the touch signal may not be reflected. As shown in fig. 2, the output signal DOUT has a data value according to or corresponding to the touch signal in a period other than the reset data period RP, but has a data value irrelevant to the touch signal in the reset data period RP. Further, even if the AFE 210 is not reset, the reset data period RP of the output signal DOUT may have a noise data value that incorrectly reflects the touch signal due to noise introduced in the reception signal RX. Accordingly, the reset data period RP of the output signal DOUT has a discontinuous data value. In this case, when the data value is discontinuous, this means that the data value is suddenly changed or the data value is not changed. As a result, the controller 220 may not extract accurate amplitude and frequency information from the output signal DOUT, and an error may occur in the touch pressure when detecting the touch coordinates and pressure based on the amplitude and frequency of the output signal DOUT.

However, the controller 220 according to the present embodiment may interpolate the data value of the reset data period RP of the output signal DOUT to generate the reconstructed output signal dout_r as shown in fig. 2, and may extract the amplitude and frequency information based on the reconstructed output signal dout_r. In other words, the controller 220 may apply a data interpolation method to the output signal DOUT, thereby recovering or reconstructing the data value of the touch signal for the reset data period RP of the output signal DOUT.

The controller 220 may generate the data value of the reset data period RP based on the data values of the periods before and after the reset data period RP among the data values of the output signal DOUT. The controller 220 may generate the data value of the reset data period RP using various data interpolation methods. The reconstructed output signal dout_r may have consecutive data values. The controller 220 may extract the correct amplitude and frequency information from the reconstructed output signal dout_r.

The reception signal RX provided from the touch panel 100 may include various noises. The received signal RX may vary due to various noise and indicators. For example, the reception signal RX may include noise generated from other components in the electronic device, light outside the touch panel 100, a charger connected to the electronic device, a display panel, and the like. Touch detection may be inaccurate due to the influence of noise.

However, in the touch detection device 10 according to the example embodiment of the present disclosure, the AFE 210 is reset (or held) during a period in which noise is present in the reception signal RX, and thus noise can be avoided. In addition, the controller 220 may reconstruct the output signal DOUT by restoring the touch signal in the reset period Trst via the data interpolation method, and may perform touch detection based on the reconstructed output signal dout_r. Accordingly, the touch detection apparatus 10 according to the embodiment of the present disclosure may minimize the influence of noise and improve the accuracy of touch detection.

The data interpolation method shown in fig. 3A and 3B may be performed by the controller 220 of fig. 1.

The output signal DOUT includes the data value output from the ADC 204, and the data value may vary with time. As described above, the data value of the reset data period (e.g., the data value of the second period P2 of fig. 3A and 3B) of the output signal DOUT corresponding to the reset period Trst of the reset signal RST may not reflect the touch signal due to noise. Accordingly, in order to generate a data value reflecting the touch signal, the controller 220 may interpolate a data value of the second period P2 based on data values of the first period P1 and the third period P3 of the output signal DOUT. In this case, the first period P1 and the third period P3 of the output signal DOUT may be referred to as continuous periods including continuous data values, and the second period P2 may be referred to as discontinuous periods including at least one discontinuous data value.

For example, as shown in fig. 3A and 3B, the controller 220 may interpolate the data value of the second period P2 by using linear interpolation. The controller 220 may generate at least one data value (data value D2 in fig. 3A and data values d2_1 and d2_2 in fig. 3B) of the second period P2 based on data values (e.g., data value D1 and data value D3) corresponding to a point in time of the second period P2 closest to the output signal DOUT.

As shown in fig. 3A, when the output signal DOUT includes one data value at time t1 of the second period P2 (for example, when the second period P2 is less than twice the sampling period), an intermediate value between the data value D1 and the data value D3 (for example, a value obtained by dividing the sum of the data value D1 and the data value D3 by 2) may correspond to the data value D2 at time t 1.

As shown in fig. 3B, when the output signal DOUT includes data values at time t1 and time t2 of the second period P2 (for example, when the second period P2 is greater than two times and less than three times the sampling period), a larger one of intermediate values generated by dividing the sum of the data value D1 and the data value D3 by 1/3 and 2/3 may correspond to the data value d2_1 at time t1, and a smaller one of the intermediate values may correspond to the data value d2_2 at time t 2.

The data interpolation method performed by the controller 220 of fig. 1 has been described with reference to fig. 3A and 3B. However, the present disclosure is not limited thereto, and various data interpolation methods may be used.

Fig. 4 is a circuit diagram of an example embodiment of AFE 210 a. Referring to fig. 4, the afe 210a may include an input buffer 201a, a filter 202a, an amplifier 203a, and an ADC 204a.

The AFE 210a of fig. 4 is an example of an implementation of the AFE 210 of fig. 1. The descriptions of the input buffer 201, the filter 202, the amplifier 203, and the ADC 204 given with reference to fig. 1 may be applied to the input buffer 201a, the filter 202a, the amplifier 203a, and the ADC 204a in fig. 4, respectively, and thus redundant descriptions will be omitted.

In the AFE 210a, the input buffer 201a may be reset in response to a reset signal RST.

The input buffer 201a may include an operational amplifier AMP, a resistor R1, and a capacitor C1, and may be implemented as a current-to-voltage converter, wherein the resistor R1 and the capacitor C1 are connected IN parallel between the input terminal IN1 and the output terminal ON 1.

The reset switch RSW may be connected between the input terminal IN1 and the output terminal ON1, and the reset switch RSW may be turned ON IN response to an activated reset signal RST. For example, the reset switch RSW may be turned on in response to an active level (e.g., a high level) of the reset signal RST.

When the reset switch RSW is in an off state, the input buffer 201a may output the sensing signal VS corresponding to the reception signal RX. The sense signal VS may vary in response to a variation of the receive signal RX. When the reset switch RSW is turned ON, the input terminal IN1 and the output terminal ON1 may be directly connected to each other, and the operation of the input buffer 201a to convert the reception signal RX into the sensing signal VS may be stopped. In this state, the input buffer 201a may output the sensing signal VS having no relation to the reception signal RX, for example, the sensing signal VS having a fixed level. Therefore, when the reset switch RSW is turned on, the output signal DOUT output by converting and amplifying the sense signal VS via the filter 202a, the amplifier 203a, and the ADC 204a may also have a data value unrelated to the reception signal RX.

As described above, according to the present embodiment, when the input buffer 201a is reset in response to the reset signal RST, the AFE 210a can be reset.

Fig. 5 is a circuit diagram of an example embodiment of AFE 210 b. Referring to fig. 5, the afe 210b may include an input buffer 201b, a filter 202b, an amplifier 203b, and an ADC204b.

AFE 210b of fig. 5 is an example of an implementation of AFE 210 of fig. 1. The descriptions of the input buffer 201, the filter 202, the amplifier 203, and the ADC204 given with reference to fig. 1 may be applied to the input buffer 201b, the filter 202b, the amplifier 203b, and the ADC204b, respectively, and thus redundant descriptions will be omitted.

In the AFE 210b, the input buffer 201b and the amplifier 203b may be reset in response to a reset signal RST.

The configuration and operation of the input buffer 201b are the same as those of the input buffer 201a of fig. 4, and redundant description will be omitted.

The amplifier 203b may include an operational amplifier AMP2 and variable resistors VR1 and VR2, and may amplify the filter output signal FOUT with a gain set according to a resistance value ratio between the variable resistors VR1 and VR 2.

The amplifier 203b may further include a first reset switch RSW1 and a second reset switch RSW2 connected to the input terminal IN 2. The first reset switch RSW1 may be turned off IN response to the activated reset signal RST to block the electrical connection between the output terminal and the input terminal IN2 of the filter 202b during the reset period Trst. In the reset period Trst, the filter output signal FOUT is not transmitted to the amplifier 203b. The second reset switch RSW2 may be turned on IN response to the activated reset signal RST to provide the common mode voltage VCM to the input terminal IN 2. For example, the common mode voltage VCM may be ground voltage. The amplifier 203b may output a ground voltage or another voltage having a fixed level as the analog output signal AOUT in the reset period Trst. In an embodiment, the amplifier 203b may further include a third reset switch RSW3 connected to the output terminal ON2, and the third reset switch RSW3 may be turned off in response to the activated reset signal RST to prevent the output of the amplifier 203b from being output to the ADC204b. Accordingly, the output signal DOUT output from the ADC204b in the reset period Trst may have a data value independent of the reception signal RX.

In fig. 4 and 5, for convenience of explanation, the circuits in the input buffers 201a and 201b and the amplifier 203b are only examples, and the input buffers 201a and 201b and the amplifier 203b may include circuits different from those shown in fig. 4 and 5. For example, the input buffers 201a and 201b and the amplifier 203b may further include other components, or may include other components instead of those shown in fig. 4 and 5.

Fig. 6 is a block diagram of an example embodiment of the touch detection device 10c, and fig. 7 is a graph showing signal waveforms of the touch detection device 10c of fig. 6 in the time domain.

Similar to the touch detection device 10 of fig. 1, the touch detection device 10c of fig. 6 may include a touch panel 100c, an AFE 210c, and a controller 220c. AFE 210c and controller 220c may constitute touch detection circuit 200c. As shown in fig. 6, the touch panel 100c may be touched by the pointer 20 (e.g., a stylus pen).

The touch panel 100c may provide the AFE 210c with a reception signal RX that varies according to the touch of the pointer 20. For example, when the pointer 20 is a stylus pen, the pointer 20 may include a resonance circuit having a variable capacitor VC and an inductor L, and a resonance signal generated from the resonance circuit may be provided to the touch panel 100 c. The pointer 20 may provide the touch panel 100c with a self-generated resonance signal or a resonance signal generated based on a transmission signal TX provided through a driving electrode (the first electrode 101c or the second electrode 102 c) of the touch panel 100 c. The sensing electrode (the first electrode 101C or the second electrode 102C) of the touch panel 100C may receive the resonance signal provided from the pointer 20 through the capacitor C2 formed between the touch panel 100C and the pointer 20 as a touch signal of the pointer 20. Thus, the reception signal RX may include a touch signal provided from the pointer 20.

The AFE 210c may generate the output signal DOUT from the received signal RX. Similar to AFE 210a shown in fig. 4 and AFE 210b shown in fig. 5, AFE 210c may include input buffer 201c, filter 202c, amplifier 203c, and ADC 204c, and may be reset in response to a reset signal RST. In fig. 6, for convenience of explanation, the circuits in the input buffer 201c and the amplifier 203c are only examples, and the input buffer 201c and the amplifier 203c may include circuits different from those shown in fig. 6.

AFE 210c may also include a frequency modulator 205c. The frequency modulator 205c may down-modulate or down-convert the frequency of the sense signal VS, thereby generating a frequency modulated signal MOUT. The frequency modulator 205c may modulate the frequency of the sensing signal VS based on a predetermined modulation frequency or modulate the frequency of the sensing signal VS based on a modulation frequency adaptively changed according to the frequency of the reception signal RX.

Although it is illustrated in fig. 6 that the input buffer 201c may be reset in response to the reset signal RST, the present disclosure is not limited thereto. As described above with reference to fig. 1, at least one component of AFE 210c (e.g., at least one of input buffer 201c, frequency modulator 205c, filter 202c, and amplifier 203 c) may be reset in response to a reset signal RST. Accordingly, AFE 210c may be reset.

Referring to fig. 7, the frequency of the reception signal RX may be higher than the frequency of the reset signal RST. In other words, the frequency (e.g., resonant frequency) of the touch signal supplied from the pointer 20 may be higher than the frequency of the reset signal RST.

When the AFE 210c is reset in the reset period Trst, the touch signal included in the reception signal RX may be removed together with noise. When the AFE 210c generates the output signal DOUT based on the sensing signal VS having the same frequency as the reception signal RX, one period of the output signal DOUT is similar to one period of the reception signal RX, and the data value of the reset data period RP of the output signal DOUT corresponding to the reset period Trst may be a fixed value independent of the touch signal. Therefore, when the frequency of the reception signal RX is higher than the frequency of the reset signal RST, even if the controller 220c interpolates the data value of the reset data period RP of the output signal DOUT, the interpolated data value is difficult to correctly reflect the touch signal.

However, in the AFE 210c according to an embodiment of the present disclosure, the frequency modulator 205c may down-modulate or down-convert the frequency of the sensing signal VS, thereby generating a frequency modulated signal MOUT, and when the frequency modulated signal MOUT passes through the filter 202c, the amplifier 203c, and the ADC 204c, an output signal DOUT may be generated. Thus, as shown in fig. 7, the frequency of the output signal DOUT may be lower than the frequency of the reception signal RX. Therefore, only the data value of the reset data period RP, which is significantly smaller than one period of the output signal DOUT, may be a fixed value independent of the touch signal. The data value of the reset data period RP may be restored to reflect the data value of the touch signal by the data interpolation of the controller 220 c.

Referring back to fig. 6, the controller 220c may include an interpolation module 221c, an amplitude and frequency detector 222c, and a signal generator 223c. The interpolation module 221c, the amplitude and frequency detector 222c, and the signal generator 223c may be operated by logic operations or the like, and may be implemented in one of hardware, software, and firmware, or a combination of hardware and software.

The signal generator 223c may generate the reset signal RST based on a timing signal Tsig provided from outside the controller 220c (and in some embodiments outside the touch detection circuit 200 c). The timing signal Tsig may be a signal indicating the presence of noise in the reception signal RX or a period at a higher level than other periods, for which noise is expected to be present. The signal generator 223c may generate a reset signal synchronized with the timing signal Tsig based on the timing signal Tsig, as described below with reference to fig. 9.

For example, the timing signal Tsig may be a horizontal synchronization signal supplied from the display driving circuit. The horizontal synchronization signal has one or more timing pulses that instruct the display drive circuit to update the timing of the pixels of the touch panel with new or updated pixel data. As described below with reference to fig. 8, display noise may occur periodically each time a pixel of the touch panel is updated, and the display noise may exist in the reception signal RX. Since the controller 220c generates the reset signal RST based on the timing signal Tsig and the AFE 210c is reset in response to the reset signal RST, the influence of display noise can be minimized.

The interpolation module 221c may apply data interpolation to the output signal DOUT to recover one or more data values of the reset data period RP of the output signal DOUT. The interpolation module 221c may distinguish the reset data period RP of the output signal DOUT based on the reset signal RST supplied from the signal generator 223 c. The interpolation module 221c may interpolate the data value of the reset data period RP based on the data values of other periods of the output signal DOUT. Accordingly, the interpolation module 221c may generate the output signal dout_r including the reconstruction reflecting the data value of the touch signal over the entire period.

Amplitude and frequency detector 222c may detect amplitude and frequency information from the reconstructed output signal dout_r. For example, the amplitude and frequency detector 222c may include a spectrum detection circuit such as a Fast Fourier Transform (FFT) circuit or a discrete time fourier transform (DFT) circuit, and may analyze the spectrum of the reconstructed output signal dout_r to thereby detect amplitude and frequency information. The controller 220c may detect the touch coordinates and touch pressure of the pointer 20 based on the amplitude and frequency information of the reconstructed output signal dout_r. The controller 220c may also change the modulation frequency of the frequency modulator 205c based on the frequency information.

Fig. 8 is a diagram for explaining display noise.

The touch panel 100 may be disposed on the display panel 300, or the touch panel 100 may be integrally formed with the display panel 300. Accordingly, parasitic capacitors CP1 and CP2 may be generated between the electrode layer of the display panel 300 and the touch panel 100. For example, a common electrode COM supplied with a common voltage Vcom may be formed in the uppermost layer of the display panel 300, and parasitic capacitors CP1 and CP2 may be generated between the common electrode COM and the electrodes 101 and 102 of the touch panel 100.

The display driving circuit 400 may update the pixels of the display panel 300 in response to the horizontal synchronizing signal Hsync. For example, the display voltage DV supplied to the pixels may be supplied to the display panel 300 row by row in synchronization with the horizontal synchronizing signal Hsync. Accordingly, noise occurs in the common voltage Vcom commonly supplied to the pixel through the common electrode COM. Noise of the common voltage Vcom may be supplied to the electrodes 101 and 102 of the touch panel 100 as display noise through the parasitic capacitors CP1 and CP2, and may be in the reception signal RX.

Specifically, when the pointer 20 is a stylus pen as in the touch detection apparatus 10c shown in fig. 6, the touch detection apparatus 10c may operate in a state where the display is turned on (i.e., when an image is displayed on the display panel 300). Accordingly, display noise may periodically occur in the reception signal RX every period in which the horizontal synchronization signal Hsync is activated.

In order to minimize the influence of display noise, the touch detection circuit 200 (e.g., the touch detection circuit 200c of fig. 6) may receive a timing signal Tsig (e.g., a horizontal synchronization signal Hsync) indicating the update timing of the pixels of the display panel 300 from the display driving circuit 400, and the AFE (e.g., the AFE 210c of fig. 6) of the touch detection circuit 200 may be synchronously reset based on the timing signal Tsig. Therefore, the influence of display noise can be reduced.

Fig. 9A to 9D are graphs showing example embodiments of a timing signal and a reset signal.

As described above with reference to fig. 7, the signal generator 223c may generate the reset signal RST based on the timing signal Tsig. In this case, the signal generator 223c may generate the reset signal RST in consideration of a delay time until display noise in the reception signal RX and a time to process the reception signal RX in the AFE 210 c. Referring to fig. 9A to 9D, the reset signal RST is synchronized with the timing signal Tsig, and the period of the reset signal RST may be the same as the period of the timing signal Tsig.

Referring to fig. 9A, the timing at which the reset signal RST changes to an active level (e.g., logic high) may be the same as the timing at which the timing signal Tsig changes to an active level. That is, the rising point (or falling point) of the reset signal RST may be the same as the rising point (or falling point) of the timing signal Tsig. However, a period TA2 in which the reset signal RST maintains an active level (i.e., a reset period) (hereinafter referred to as an active period TA2 of the reset signal RST) may be greater than a period TA1 in which the timing signal Tsig maintains an active level (hereinafter referred to as an active period TA1 of the timing signal Tsig). In other words, the duty ratio of the reset signal RST may be higher than the duty ratio of the timing signal Tsig.

Referring to fig. 9B, the reset signal RST may be a delayed version of the timing signal Tsig. The reset signal RST may be delayed by a delay amount D greater than the timing signal Tsig. The rising point (or falling point) of the reset signal RST may be later than the rising point (or falling point) of the timing signal Tsig. The active period TA2 of the reset signal RST (i.e., the reset period) may be the same as the active period TA1 of the timing signal Tsig. In one embodiment, the delay amount D may be smaller than the active period TA1 of the timing signal Tsig.

Referring to fig. 9C, the reset signal RST may be delayed by a delay amount D with respect to the timing signal Tsig, and an active period TA2 of the reset signal RST may be greater than an active period TA1 of the timing signal Tsig.

Referring to fig. 9D, the reset signal RST may be faster than the timing signal Tsig. That is, the reset signal RST may be advanced by the advance a with respect to the timing signal Tsig. The rising point (or falling point) of the reset signal RST may be faster than the rising point (or falling point) of the timing signal Tsig. In an embodiment, the advance a may be smaller than the effective period TA1 of the timing signal Tsig. In an embodiment, the active period TA2 of the reset signal RST may be greater than the active period TA1 of the timing signal Tsig. In some embodiments, the timing signal Tsig (e.g., hsync) may occur in a predetermined or known pattern or frequency, or the time interval between successive active level pulses of the timing signal Tsig (e.g., hsync) may be determined by the touch detection circuitry 200 (e.g., touch detection circuitry 200c of fig. 6). This may enable the controller 220 (e.g., the touch detection circuit 200c of fig. 6) to cause a rising edge of the active level of the pulse of the reset signal RST to occur before a rising edge of the active level of the pulse of the timing signal Tsig (Hsync), for example, as shown in fig. 9D.

Although the reset signal RST generated based on the timing signal Tsig has been described with reference to fig. 9A to 9D, these are merely example embodiments, and the present disclosure is not limited thereto. The reset signal RST may be variously changed within a range in which the reset signal RST is generated based on the timing signal Tsig.

As described with reference to fig. 1, the controller 220 may determine a period in which noise exists in the reception signal RX based on the output signal DOUT, and may generate the reset signal RST. This will be described with reference to fig. 10 and 11.

Fig. 10 is a block diagram of an example embodiment of a touch detection circuit 200d, and fig. 11 is a graph showing a reset signal generation method of the signal generator 223d in fig. 10.

Referring to fig. 10, the touch detection circuit 200d may include an AFE 210d and a controller 220d.

The AFE 210d may generate an output signal DOUT based on the received signal RX and may include an input buffer 201d and an ADC 204d. AFE 210d may further include other components. For example, AFE 210d may further include filters, gain amplifiers, frequency modulators, etc. as described above with reference to fig. 1, 4, 5, and 6.

The controller 220d may control the AFE 210d and may detect touch coordinates and touch pressure based on the output signal DOUT of the AFE 210d. The controller 220d may include an interpolation module 221d and a signal generator 223d. Although not shown in fig. 10, the controller 220d may also include an amplitude and frequency detector. The signal generator 223d may generate the reset signal RST and supply the reset signal RST to the AFE 210d. The AFE 210d may be periodically reset in response to the reset signal RST, and the interpolation module 221d may perform data interpolation on the output signal DOUT provided from the periodically reset AFE 210d, thereby generating a reconstructed output signal dout_r.

The signal generator 223d may generate the reset signal RST based on an initial signal (e.g., an initial output signal dout_i) of the output signal DOUT supplied from the AFE 210 d. The initial output signal dout_i represents the output signal DOUT output from the AFE 210d in an operation (e.g., a set operation, a test operation, or an initialization operation) before the touch detection circuit 200d performs touch detection.

Referring to fig. 11, the data value of the initial output signal dout_i may reflect noise of the reception signal RX. The signal generator 223d may determine a period in which noise occurs based on the initial output signal dout_i, and may generate a reset signal RST based on a result of the determination. In an embodiment, the signal generator 223d may determine a period in which the abnormal data value is detected in the initial output signal dout_i, and may provide the reset signal RST periodically having an active level based on the period and duration of the period in which the abnormal data value is detected.

Fig. 12 is a block diagram of an example embodiment of a touch detection circuit 200e, and fig. 13A to 13C are graphs showing internal signals of the AFE 210e of fig. 12 in the frequency domain.

Touch detection circuit 200e may include AFE 210e and controller 220e. The AFE 210e may include an input buffer 201e, a frequency modulator 205e, a filter 202e, an amplifier 203e, and an ADC 204e, and the controller 220e may include an interpolation module 221e, an amplitude and frequency detector 222e, and a signal processor 223e. The configuration and operation of the touch detection circuit 200e are similar to those of the touch detection circuit 200c of fig. 6. Therefore, redundant description will be omitted.

Referring to fig. 12, the frequency modulator 205e may include a mixer 21e and a local oscillator 22e, and may adaptively change a modulation frequency.

The mixer 21e may output the frequency modulation signal MOUT by heterodyning the sense signal VS and the local oscillator signal LO supplied from the input buffer 201 e. The mixer 21e may shift the frequency of the sense signal VS according to the frequency of the local oscillator signal LO, i.e. the modulation frequency (or shift frequency).

The local oscillator 22e may provide the local oscillator signal LO to the mixer 21e, and may change the frequency (i.e., the modulation frequency) of the local oscillator signal LO in response to the frequency setting signal FSET provided from the controller 220 e. For example, the local oscillator 22e may include a Phase Locked Loop (PLL) or a Delay Locked Loop (DLL).

The frequency of the local oscillator signal LO may be set based on the frequency of the touch signal and the set passband of the filter 202 e. Thus, the mixer 21e heterodynes the frequency band of the sense signal VS based on the frequency of the local oscillator signal LO, thereby shifting the frequency band of the touch signal included in the sense signal VS to the set passband of the filter 202 e.

Fig. 13A, 13B, and 13C show the sensing signal VS, the frequency modulation signal MOUT, and the filter output signal FOUT in the frequency domain, respectively.

Referring to fig. 13A, the sensing signal VS generated from the reception signal RX may include a low frequency band NL and a high frequency band NH caused by noise, in addition to the frequency band S caused by the touch signal. That is, the sensing signal VS may include a high frequency band NH caused by noise having a frequency higher than that of the frequency band S caused by the touch signal and a low frequency band NL caused by noise having a frequency lower than that of the frequency band S caused by the touch signal.

The frequency modulator 205e may heterodyne the sense signal VS and the local oscillator signal LO such that the filter 202e easily removes the frequency band caused by noise and easily extracts the frequency band S caused by the touch signal.

The local oscillator signal LO may have a frequency f_l0 close to the frequency band S caused by the touch signal. By heterodyning based on the frequency f_lo of the local oscillator signal LO, the frequency band S caused by the touch signal may be shifted to be spaced apart from the noise-caused low frequency band NL and high frequency band NH, for example in a lower frequency range than the ranges to which NL and NH are shifted.

As shown in fig. 13B, the low frequency band NL of the sensing signal VS, the frequency band S caused by the touch signal, and the high frequency band NH of the sensing signal VS shown in fig. 13A may be shifted to frequency bands NL ', S ', and NH ', respectively, which correspond to the differences Δ1, Δ2, and Δ3 from the frequency f_lo of the local oscillator signal LO. Accordingly, the frequency bands NL ' and NH ' caused by noise may be located at one side of the frequency band S ' caused by the touch signal.

Referring to fig. 13C, the frequency band S' of fig. 13B may be extracted by a filter 202e (e.g., a low pass filter) having a CUT-off frequency F CUT. That is, when the frequency modulation signal MOUT of fig. 13B passes through the filter 202e having the CUT-off frequency f_cut, the frequency band S' caused by the touch signal is located in the set pass band of the filter 202e and thus is output through the filter 202e. However, the bands NL 'and NH' caused by noise are located in the stop band of the filter 202e, and thus may not pass through the filter 202e. Therefore, as shown in fig. 13C, the frequency bands NL 'and NH' caused by noise in the filter output signal FOUT can be attenuated.

The controller 220e may generate a frequency setting signal FSET for setting a modulation frequency (i.e., the frequency f_lo of the local oscillator signal LO) and provide the frequency setting signal FSET to the frequency modulator 205e such that a frequency band caused by the touch signal is included in a set pass band of the filter 202e and a frequency band caused by noise is included in a stop band of the filter 202e.

As shown in fig. 13B, the frequency offset Δ1, i.e., the difference between the frequency band S caused by the touch signal and the frequency f_lo of the local oscillator signal LO may be set such that the difference is included in the set passband of the filter 202e, and the frequency f_l0 of the local oscillator signal LO may vary according to the frequency band S caused by the touch signal. Since the frequency offset Δ1 is determined by the CUT-off frequency f_cut of the filter 202e, the frequency offset Δ1 may have a constant value.

In an embodiment, the touch detection circuit 200e may operate in a coarse mode and a fine mode. The controller 220e may coarsely detect a touch in the coarse mode and may finely detect a touch in the fine mode based on the detection result. In the coarse mode, the controller 220e may set the frequency f_lo of the local oscillator signal LO, i.e., the modulation frequency, based on the predicted frequency of the touch signal (e.g., the frequency of the transmit signal) and the frequency offset Δ1. As described above, the controller 220e may detect the amplitude and frequency of the touch signal based on the reconstructed output signal dout_r. In the fine mode, the controller 220e may set the frequency f_lo of the local oscillator signal LO based on the frequency of the touch signal detected in the coarse mode and the frequency offset Δ1. Accordingly, the modulation frequency can be adaptively changed, and the noise removal performance of the frequency modulator 205e and the filter 202e can be improved. In the fine mode, the controller 220e may detect the magnitude and frequency of the touch signal based on the reconstructed output signal dout_r, and may detect the touch coordinates and pressure based on the magnitude and frequency of the touch signal.

Fig. 14A and 14B are circuit diagrams of example embodiments of AFEs 210f and 210 g.

Fig. 14A and 14B illustrate an embodiment for processing a received signal RX in a differential mode.

Referring to fig. 14A, similar to the AFE 210e of fig. 12, the AFE 210f may include an input buffer 201f, a frequency modulator 205f, a filter 202f, an amplifier 203f, and an ADC 204f.

AFE 210f may also include a selector 206f. The selector 206f may select a corresponding reception signal RX from among reception signals received from the touch panel and supply the selected reception signal RX to the input buffer 201f. The selector 206f may be implemented with a multiplexer, a switching circuit, or the like.

The input buffer 201f may receive the reception signal RX and the common mode voltage VCM, and may output the sensing signals VSn and VSp as differential signals. The input buffer 201f may include reset switches RSW1 and RSW2 connected to the input terminal and the output terminal, and the reset switches RSW1 and RSW2 may be turned on in response to a reset signal RST supplied from a controller (e.g., the controller 220e of fig. 12), thereby resetting the input buffer 201f.

The frequency modulator 205f may output frequency modulation signals MOUTn and MOUTp by heterodyning the sense signals VSn and VSp based on the local oscillator signal LO provided from the local oscillator 22 f. The frequency of the local oscillator signal LO (i.e., the modulation frequency) may be set according to a frequency setting signal FSET provided from the controller.

The filter 202f may output filter output signals FOUTn and FOUTp as differential signals by filtering the frequency modulation signals MOUTn and MOUTp at the same cut-off frequency as each other.

The amplifier 203f may include a differential amplifier, and may output analog output signals AOUTn and AOUTp as differential signals by amplifying the filter output signals FOUTn and FOUTp.

Referring to fig. 14b, the afe 210g may include an input buffer 201g, a filter 202g, an amplifier 203g, an ADC 204g, a frequency modulator 205g, and a selector 206g.

The selector 206g may differentially supply the two reception signals RXn and RXp supplied from two adjacent sensing electrodes among the reception signals received from the touch panel to the input buffer 201 g. The input buffer 201g may generate two differential sense signals VSn and Vsp by converting the two received signals RXn and RXp. As described with reference to fig. 14A, the frequency modulator 205g, the filter 202g, the amplifier 203g, and the ADC 204g may process the two differential sense signals VSn and Vsp in a differential mode, thereby generating the output signal DOUT.

Fig. 15 is a flowchart of an example embodiment of a touch detection method.

The touch detection method of fig. 15 is a method of detecting a touch of a pointer occurring in a touch panel, and may be performed in the above-described touch detection circuit (e.g., the touch detection circuit 200 of fig. 1, the touch detection circuit 200c of fig. 6, the touch detection circuit 200d of fig. 10, or the touch detection circuit 200e of fig. 12). Hereinafter, the touch detection method of fig. 15 will be described with reference to fig. 1.

Referring to fig. 15, the afe 210 may generate a first output signal (i.e., an output signal DOUT) including a digital data value based on a reception signal RX provided from the touch panel 100 (operation S110). For example, the AFE 210 may convert a reception signal RX, which is an Alternating Current (AC) signal, into a sensing signal VS, amplify the gain of the sensing signal VS, and convert a signal having the amplified gain into a digital data value. The AFE 210 may filter the sensing signal VS to remove noise and may down-convert the frequency of the sensing signal VS.

The AFE 210 may be periodically reset in response to the reset signal RST. In response to the reset signal RST, at least one component of AFE 210 (e.g., input buffer 201, filter 202, and amplifier 203) may be reset. Accordingly, at least one of the operation of the input buffer 201 converting the reception signal RX into the sensing signal VS, the operation of the filter 202 performing filtering on the sensing signal VS (or the frequency modulation signal), and the operation of the amplifier 203 amplifying the gain of the input signal may include a period of performing periodic reset.

The reset signal RST may have an active level in a period in which noise is present in the reception signal RX. Since the AFE 210 is reset in response to the reset signal RST, noise can be avoided. In an embodiment, the reset signal RST may be a signal synchronized with a timing signal (e.g., a horizontal synchronization signal) supplied from the display driving circuit.

The controller 220 may perform data interpolation on the first output signal, thereby generating a second output signal, i.e., a reconstructed output signal dout_r (operation S120).

As described above, when the AFE 210 is periodically reset, the data value of the reset data period of the output signal DOUT corresponding to the reset period of the reset signal RST is independent of the reception signal RX and does not reflect the touch signal. Even if the AFE 210 is not periodically reset, a noise data period may periodically exist in the output signal DOUT, and a data value of the noise data period incorrectly reflects the touch signal.

The controller 220 may perform data interpolation to restore the data value of the reset data period (or the noise data period) of the first output signal (i.e., the output signal DOUT) to a data value reflecting the touch signal. The controller 220 may generate the data value of the reset data period by interpolating the data value of a point adjacent to the reset data period among the data values of the periods other than the reset data period of the first output signal. Accordingly, the second output signal including the data value accurately reflecting the touch signal can be generated.

The controller 220 may detect a touch of the pointer based on the second output signal (i.e., the reconstructed output signal dout_r) (operation S130). For example, the controller 220 may detect the amplitude of the second output signal and calculate the touch coordinates based on the amplitude. The controller 220 may also detect the frequency of the second output signal and detect the touch pressure based on the frequency.

Fig. 16 is a flowchart of an example embodiment of a touch detection method.

The touch detection method of fig. 16 is a method of detecting a touch of a pointer occurring in the touch panel, and may be performed in the touch detection circuit 200e of fig. 12. Hereinafter, the touch detection method of fig. 16 will be described with reference to fig. 12.

The touch detection circuit 200e may perform fine sensing (operation S200) after performing coarse sensing (operation S100). The touch detection circuit 200e may roughly detect touch information by performing rough sensing, and precisely detect a touch by performing fine sensing based on the roughly detected touch information.

Referring to fig. 16, in the coarse sensing, the AFE 210e may generate a first output signal (i.e., an output signal DOUT) according to the coarse sensing (operation S210). The AFE 210e may generate the first output signal according to operation S110 of fig. 15 described above. In this case, in the operation of down-converting the frequency of the sense signal VS, the sense signal VS may be heterodyned based on the local oscillator signal LO supplied from the local oscillator 22e, and the frequency f_lo (i.e., the modulation frequency) of the local oscillator signal LO may be coarsely set based on a frequency offset set according to the cut-off frequency of the filter 202e and the predicted frequency of the first output signal.

The controller 220e may generate a second output signal, i.e., the reconstructed output signal dout_r, based on the first output signal of the AFE 210e, and may detect a frequency of the second output signal (operation S220). The controller 220e may perform data interpolation on the first output signal, thereby generating a second output signal. The first output signal may have a periodic data value that is independent of the data signal, and the controller 220e may restore the data value to a data value associated with the touch signal via data interpolation, thereby generating a second output signal, i.e., a reconstructed output signal dout_r. The frequency of the second output signal may reflect the frequency of the touch signal.

In the fine sensing, the controller 220e may change the frequency (i.e., the modulation frequency) of the local oscillator signal LO based on the detected frequency (operation S230). The controller 220e may reset the modulation frequency based on the frequency offset and the detected frequency.

The AFE 210e may generate a first output signal according to fine sensing (operation S240). The AFE 210e may regenerate the first output signal according to operation S110 of fig. 15 described above. In operation of down-converting the frequency of the sense signal VS, AFE 210e may heterodyne the sense signal VS based on the local oscillator signal LO having a changed frequency.

The controller 220e may generate a second output signal based on the first output signal of the AFE 210e and detect a touch of the pointer based on the second output signal (operation S250). The AFE 210e may perform data interpolation on the first output signal to generate a second output signal, i.e., a reconstructed output signal. The controller 220e may calculate touch coordinates and touch pressure of the pointer based on the amplitude and frequency of the second output signal.

Fig. 17 is a block diagram of an example embodiment of a system 1000 including a touch detection device.

The system 1000 may be a computing system such as a personal computer, a network server, a tablet PC, an electronic reader, a PDA, a PMP, a mobile phone, a smart phone, or a wearable device, or may be a control system for controlling a vehicle, a mechanical device, a manufacturing facility, a door, or the like. As shown in fig. 17, the system 1000 may include a touch detection device 10 and a Central Processing Unit (CPU) 30. The system 1000 may also include other components, such as a sensor module and a display device.

CPU 30 may control the overall operation of system 1000. For example, CPU 30 may control the operation of system 1000 by executing a series of instructions stored in memory. The CPU 30 may recognize a touch position and a touch pressure based on the touch detection signal TDET received from the touch detection device 10, and control operations of other components of the system 1000 based on the touch position and the touch pressure. For example, the CPU 30 may display an image on the display device, and may display an image change according to a touch position and a touch pressure on the display device.

The touch detection device 10 may include a touch panel 100 and a touch detection circuit 200. The touch detection circuit 200 may provide the transmission signal TX to the touch panel 100 and may receive the reception signal RX from the touch panel 100. Touch detection circuit 200 may include an AFE and a controller. As described above with reference to fig. 1 and the like, the AFE may be periodically reset, and the controller may generate a reconstructed output signal by restoring the data value of the reset period of the output signal via data interpolation. The controller may detect the touch coordinates and the touch pressure based on the reconstructed output signal, and may provide the touch coordinates and the touch pressure as the touch detection signal TDET to the CPU 30.

Fig. 18 is a block diagram of an example embodiment of a system 2000.

As shown in fig. 18, the system 2000 may include a CPU 2500, a memory 2600, a network interface 2700, a touch panel 2100, a display panel 2300, and a touch display driver integrated circuit (DDI) 2800. Unlike the case shown in fig. 18, the CPU 2500 and other components of the system 2000 can be connected to each other and communicate with each other through a bus.

CPU 2500 may control the overall operation of system 2000 by executing instructions stored in memory 2600 or in a memory included in CPU 2500. For example, the CPU 2500 may provide image data to the touch display driving circuit 2400, recognize an external input by interpreting a touch of a pointer to an image output to the display panel 2300, and perform at least one predetermined function in response to the external input. In an embodiment, the CPU 2500 may be a system on a chip (SoC) including a processor, a bus, and functional blocks, and may be referred to as an Application Processor (AP).

The memory 2600 may be accessed by the CPU 2500 and may include non-volatile memory such as Electrically Erasable Programmable Read Only Memory (EEPROM), flash memory, phase change random access memory (PRAM), resistive Random Access Memory (RRAM), nano Floating Gate Memory (NFGM), polymer random access memory (PoRAM), magnetic Random Access Memory (MRAM), or Ferroelectric Random Access Memory (FRAM), or may include volatile memory such as Dynamic Random Access Memory (DRAM), static Random Access Memory (SRAM), mobile DRAM, double data rate synchronous dynamic random access memory (DDR SDRAM), low power DDR (LPDDR) SDRAM, graphic DDR (GDDR) SDRAM, or Rambus Dynamic Random Access Memory (RDRAM).

Network interface 2700 may provide CPU 2500 with an interface to a network external to system 2000. For example, the network interface 2700 may be connected to a wired or wireless network, and may transmit a signal received from the network to the CPU 2500, or transmit a signal received from the CPU 2500 to the network.

The touch DDI 2800 may be implemented as a single chip, and may include a touch detection circuit 2200 for controlling the touch panel 2100 and a touch display driving circuit 2400 for controlling the display panel 2300. The touch detection circuit 2200 may include an AFE 2210 and a touch controller 2220, and the touch display driving circuit 2400 may include an output driver 2310 and a display controller 2320. The touch panel 2100 may be disposed on the display panel 2300. The touch panel 2100 may be integrally formed with the display panel 2300. The touch panel 2100 may transmit an output of the display panel 2300, and the touch panel 2100 and the display panel 2300 may be collectively referred to as a touch screen.

The AFE 2210 may provide the transmission signal TX to the touch panel 2100 and may receive the reception signal RX from the touch panel 2100. The AFE 2210 may convert and amplify the reception signal RX to generate an output signal, and the touch controller 2220 may detect touch information of the pointer based on the output signal. The AFE 2210 may be periodically reset in response to a reset signal supplied from the touch controller 2220, and thus the output signal may have a periodic data value independent of the touch signal in a reset period. The touch controller 2220 may generate the reconstructed output signal by performing data interpolation on the output signal and recovering one or more data values of a reset period of the output signal. The controller may detect touch information based on the reconstructed output signal and provide a signal including the touch information to the CPU 2500.

The display controller 2320 may convert image data provided by the CPU 2500 into a signal for display on the display panel 2300, and the output driver 2310 may output the display output signal dis_out under the control of the display controller 2320. As shown in fig. 18, a display controller 2320 may be in communication with touch controller 2220. For example, the display controller 2320 may provide a timing signal Tsig including information about display timing to the touch controller 2220. For example, the timing signal Tsig may be a horizontal synchronization signal indicating update timing of the pixels of the display panel 2300. The touch controller 2220 may provide a signal including information about an operation mode (e.g., information about whether to enter a standby mode) to the display controller 2320.

Although not shown in fig. 18, the touch DDI 2800 may include a memory accessed by the touch controller 2220 and/or the display controller 2320, and may further include a power circuit for powering the AFE 2210 and the output driver 2310. Unlike the case shown in fig. 18, the touch controller 2220 and the display controller 2320 may communicate with the CPU 2500 through separate interfaces (e.g., loSSI and I2C).

While the present inventive concept has been particularly shown and described with reference to embodiments thereof, it will be understood that various changes in form and details may be made therein without departing from the spirit and scope of the appended claims.

Claims

1. A touch detection device, comprising:

a current-to-voltage converter configured to convert a reception signal received from the touch panel into a sensing signal, and further configured to periodically reset for a first period of time in response to a reset signal;

an analog-to-digital converter configured to convert an analog signal generated based on the sensing signal into a first digital output signal;

a controller configured to generate a second digital output signal based on the first digital output signal by performing data interpolation on a first portion of the first digital output signal, wherein the first portion of the first digital output signal corresponds to the first period of time, and

A frequency modulator configured to generate a frequency modulated signal by heterodyning a frequency of the sense signal based on a set modulation frequency.

2. The touch detection device of claim 1, wherein the current-to-voltage converter is configured to output a voltage having a level independent of the received signal for the first period of time in response to the reset signal.

3. The touch detection device of claim 1, further comprising:

a filter configured to output a low frequency band of the frequency modulation signal as a filter output signal based on a set passband; and

an amplifier configured to generate the analog signal by amplifying the filter output signal with a set gain.

4. A touch detection device according to claim 3, wherein the frequency of the sense signal is higher than the frequency of the reset signal.

5. The touch detection device of claim 3, wherein the controller is configured to detect a frequency of the second digital output signal and is further configured to change a modulation frequency of the frequency modulator based on the frequency of the second digital output signal and the set passband.

6. The touch detection device of claim 3, wherein the amplifier is configured to be periodically reset for the first period of time in response to the reset signal.

7. The touch detection device according to claim 1, wherein the controller is configured to generate the reset signal based on a timing signal supplied from a display driving circuit that drives a display panel adjacent to the touch panel.

8. The touch detection device according to claim 7, wherein the timing signal includes a horizontal synchronization signal that instructs the display drive circuit to update timing of pixels of the display panel with new pixel data.

9. The touch detection device of claim 7, wherein the reset signal is activated in synchronization with the timing signal and an active period of the reset signal is less than or greater than an active period of the timing signal.

10. The touch detection device of claim 7, wherein an active period of the reset signal is earlier or later than an active period of the timing signal.

11. The touch detection device of claim 1, wherein the controller is configured to analyze a noise component of the first digital output signal to determine a period of time in which noise is present in the received signal, and is further configured to generate the reset signal having an active level in the period of time in which noise is present in the received signal.

12. The touch detection device of claim 1, wherein the controller is configured to detect the magnitude and frequency of the second digital output signal and is further configured to detect touch coordinates and touch pressure generated on the touch panel based on the magnitude and frequency of the second digital output signal.

13. The touch detection device of claim 1, wherein the controller is configured to perform data interpolation based on first and second data values corresponding to first and second points in time, respectively, wherein the first and second points in time are adjacent to the first portion of the first digital output signal.

14. A touch detection device for processing a received signal that varies with a touch of a pointer on a touch panel, the touch detection device comprising:

an analog front end configured to generate a first output signal by converting and amplifying the received signal, wherein the analog front end is periodically reset in response to a reset signal to generate the first output signal having a discontinuous data value; and

a controller configured to generate a second output signal having a continuous data value by interpolating a discontinuous period of the first output signal having a discontinuous data value based on the data value of the continuous period, and further configured to detect a frequency of the second output signal,

Wherein the analog front end comprises:

an input buffer configured to convert the received signal into a sense signal; and

15. The touch detection device according to claim 14, wherein the controller is configured to generate the reset signal based on a timing signal indicating timing for updating pixels of a display panel adjacent to the touch panel in units of rows.

16. The touch detection device of claim 14, wherein the analog front end comprises:

a filter configured to filter frequency components of the frequency modulation signal based on a set passband and output a filter output signal; and

an amplifier configured to generate an analog output signal by amplifying the filter output signal,

wherein at least one of the input buffer, the frequency modulator, the filter, and the amplifier is reset in response to the reset signal.

17. The touch detection device of claim 16, wherein the frequency of the received signal varies with the touch pressure of the pointer and the controller is configured to calculate the touch pressure of the pointer based on the frequency of the second output signal.

18. A touch detection device for processing a received signal that varies with a touch of a pointer on a touch panel, the touch detection device comprising:

an analog front end configured to generate a first output signal by converting and amplifying the received signal; and

a controller configured to interpolate a second data value of a second period of the first output signal based on a first data value of a first period of the first output signal before a second period of the first output signal and a third data value of a third period of the first output signal after the second period.

19. The touch detection device according to claim 18, wherein the controller is configured to determine the second period based on a horizontal synchronization signal indicating timing for updating pixels of a display panel adjacent to the touch panel in units of rows.

20. The touch detection device of claim 19, wherein the analog front end is reset within a reset period in response to the horizontal synchronization signal or a reset signal generated based on the horizontal synchronization signal, and the second period of the first output signal corresponds to the reset period.

21. A method of detecting a touch by processing a received signal that varies with the touch of a pointer on a touch panel, the method comprising:

generating an output signal based on the received signal, wherein the output signal has a data value corresponding to a change in the received signal;

generating a reconstructed output signal by interpolating at least one data value of a second period of the output signal between a first period and a third period of the output signal based on the data value of the first period and the data value of the third period of the output signal; and

the amplitude and frequency of the reconstructed output signal are detected.

22. The method of claim 21, wherein generating the output signal comprises: the received signal is processed by an analog front end to generate the output signal, wherein the analog front end stops operation during a reset period in response to a reset signal to generate the output signal having a discontinuous data value in the second period corresponding to the reset period.

23. The method of claim 22, wherein the reset signal is generated based on a horizontal synchronization signal, wherein the horizontal synchronization signal indicates a timing for updating pixels of a display panel adjacent to the touch panel.

24. The method of claim 21, wherein generating the output signal comprises:

converting the received signal into a sensing signal;

generating a low frequency signal by down-modulating the frequency of the sensing signal;

filtering noise of the low frequency signal to output a noise filtered low frequency signal;

generating an analog signal by amplifying the noise filtered low frequency signal; and

the output signal is generated by converting the analog signal to a digital signal.

25. The method of claim 24, wherein at least one of the conversion of the received signal, the generation of the low frequency signal, the filtering of the noise, and the generation of the analog signal comprises a period of time in which operation is periodically stopped according to a reset signal.